High-temperature Aharonov-Bohm effect in transport through a single-channel quantum ring

Abstract

We overview transport properties of an Aharonov-Bohm interferometer made of a single channel quantum ring. Remarkably, in this setup, essentially quantum effects survive thermal averaging: the high temperature tunneling conductance G of a ring shows sharp dips (antiresonances) as a function of magnetic flux. We dis cuss effects of the electron-electron interaction, disorder, and spin-orbit coupling on the Aharonov-Bohm transport through the ring. The interaction splits the dip into series of dips broadened by dephasing. The physics behind this behavior is the persistent current blockade: the current through the ring is blocked by the circular current inside the ring. Dephasing is then dominated by tunneling induced fluctuations of the circu lar current. The short range disorder broadens antiresonances, while the long range one induces additional dips. In the presence of a spin-orbit coupling, G exhibits two types of sharp antiresonances: Aharonov-Bohm and Aharonov-Casher ones. In the vicinity of the antiresonances, the tunneling electrons acquire spin polar ization, so that the ring serves as a spin polarizer. Fig. 1. Single channel quantum ring and its energy levels.

Coherent spin transport through helical edge states of topological insulator

“…We have demonstrated the existence of interference-induced effects, which are robust to the temperature, i.e., survive under the condition Eq. 5, and can therefore be obtained for relaxed experimental conditions (for discussion of this regime in conventional interferometers, see refs 41,[58][59][60][61] ). Specifically, we have found that G is structureless in ballistic case but shows periodic dependence on dimensionless flux ϕ = Φ/Φ 0 (here, Φ 0 = hc/e is the flux quantum), with the period 1/2, in the presence of a single magnetic impurity in one of the interferometer's shoulders.…”

Spin and charge transport through a helical Aharonov-Bohm interferometer with a strong magnetic impurity

“…We see that sharp antiresonances appear at half-integer and integer values of the flux, φ by contrast to conventional interferometers, where only half-integer resonances exist [29]. The difference is related to the absence of backscattering by non-magnetic contacts in the case of helical edge states [31].…”

“…The high-temperature regime, T ∆, was already studied for single-channel AB interferometers made of conventional materials [26][27][28][29][30] and it was demonstrated that flux-sensitive interference effects survive in this case. Recently, we discussed high-temperature electron and spin transport in AB interferometers based on helical edge states of TI [31,32].…”

Resonant inverse Faraday effect in nanorings

“…Remarkably, the coupling strength α drops out from the result of Eq. (38). Thus, the radiation-induced contribution to current might be large even in the weakcoupling regime, and decays as T −1 in contrast to the persistent current contribution which decays exponentially with temperature.…”

“…To conclude the comparison of I per and I rad , we note that persistent current might show up indirectly at high temperatures. In particular, it was demonstrated in a series of publications [36][37][38] that the tunneling current through a single-channel quantum ring is blocked by persistent current. This effect, caused by an interplay of quantum interference and charge quantization, has been named the persistent-current blockade (PCB) in analogy with the well-known Coulomb blockade.…”